1. Field of Invention
This invention is directed to metal forging and, more particularly, to apparatuses that can be used in a forging apparatus to near net warm forge parts having complex shapes from axi-symmetrical workpieces (or billets), and also to methods utilizing the apparatuses to produce such parts from such workpieces.
2. Description of Related Art
The forging of small, complex shaped metal parts is problematic. Such parts can be produced by hot forging processes. However, these processes are not completely satisfactory for various reasons, including that hot forging processes result in significant flash (excess material) being formed on parts. This flash must be removed by a machining operation such as grinding, which increases the cost and difficulty of producing the finished parts. Furthermore, hot forging processes inefficiently utilize workpiece material because the flash is waste material. Accordingly, it is desirable to produce such parts by a forging process other than hot forging.
Forging processes that eliminate some of the problems associated with hot forging processes are near net warm forging processes. In near net warm forging processes, the finished parts have a volume substantially equal to the volume of the workpieces (billets). The parts forged by near net warm forging processes typically have only a small amount of excess material or flash that must be removed to finish the parts. This small amount of flash can normally be removed by relatively simple secondary operations. Thus, as compared to hot forging and other forging techniques, near net warm forging processes can reduce processing costs by efficient material utilization, and by simplifying the secondary operations that are necessary to produce the finished parts.
However, while known near net warm forging processes can produce parts of certain relatively simple configurations with high dimensional accuracy, these known near net warm forging apparatuses and processes cannot be employed to effectively manufacture certain complex shaped parts for a number of reasons. Particularly, as stated, to near net warm forge parts, the workpiece volume must be approximately equal to the volume of each finished part. Workpieces that are typically used in warm forging have axi-symmetrical shapes such as generally cylindrical shapes, so that the workpieces readily fit in the die cavities in a single orientation. Stated differently, the workpieces used in warm forging apparatuses and processes are usually axi-symmetrical and elongated along the axis of symmetry so that the workpieces can only fit in the die cavities in a given orientation. For example, the length of the workpiece along the axis may be longer than all dimensions of the cavity other than the length of the cavity, so that the length can only fit in the cavity in one orientation.
The size and geometry of the die cavity are, of course, dependent on the size and shape of the finished parts. However, in some instances, the size and geometry of the die cavity (required to form a particular part configuration) are such that an axi-symmetrical workpiece having the necessary volume to produce the part will not fit in the die cavity. Stated differently, the configuration of a specific part may be such that an axi-symmetrical workpiece having the necessary volume will not fit in the die cavity.
It is not possible to overcome this problem by using a workpiece having a smaller volume than the finished part. Although such underpacked workpieces may fit entirely into the die cavity, the resulting forged parts would be underfilled and, accordingly, defective. Thus, this solution is not satisfactory.
Therefore, known near net warm forging apparatuses and processes are not capable of producing certain parts using axi-symmetrical workpieces that will not fit in the die cavities. Yet, it is desirable to produce such parts by near net warm forging because of the advantages of near net warm forging. Thus, there is a need for apparatuses and methods that can be used to near net warm forge certain complex shaped metal parts that overcome the above-described problems.